In 2018, geochemical analysis was conducted using portable-XRF of 303 obsidian artifacts from four archaeological sites in the Majes Valley, Arequipa Peru. The four sites correspond to the Middle Horizon period (AD 600-1000) and include Santa Rosa II, La Angostura, El Tambo, and Pakaytambo. Comparisons to geologic obsidian samples allowed for the positive identification of artifacts to their corresponding geologic source. Results indicate the use of six discrete obsidian sources from the south-central Andes. Three of the sources are found relatively close to the study area and include Alca-1, Alca-4, and Anillo. A smaller quantity of artifacts was characterized as Quispisisa, Jampatilla, and Lisahuacho found to the north of Arequipa in the neighboring departments of Ayacucho and Apurimac. This data is a component of the PhD dissertation entitled Networks of Empire: The Role of Infrastructure in Wari State Expansion in Arequipa, Peru (AD 600-1000) by David A. Reid (University of Illinois at Chicago). This research was conducted in collaboration with Patrick Ryan Williams at The Field Museum of Natural History and the institution’s Elemental Analysis Facility. Funding was provided by the National Science Foundation’s Doctoral Dissertation Research Improvement Award (#1854651).